The applicant's NIMH-supported research focuses on evaluating the cost-effectiveness of HIV prevention interventions for at-risk populations. The proposed research program encompasses four main objectives -- each of which is associated with multiple projects. The first is to evaluate the cost-effectiveness of several community-level HIV prevention interventions. His second goal is to refine existing methods for conducting HIV prevention cost-effectiveness analyses, including adjusting for self-presentation and recall bias on self-reported risk behaviors; developing methods of extrapolating sexual behavior data to estimate "lifetime" risks of intervention participants; adjusting for the persistence/decay of intervention effectiveness over time; and investigating how inter- and intra-personal variability in the probability of HIV transmission impacts the results of modeling exercises. The third goal is to examine the relationship of HIV to other STDs, and to incorporate non-HIV STDs into sexual risk reduction intervention cost-effectiveness models. Finally, he plans to develop dynamic models of HIV/STD epidemiology for use in cost-effectiveness analyses of risk reduction interventions, given the type of individual-level data that are commonly collected in intervention efficacy trials. The applicant's career development plan describes how a K award would facilitate his progress toward senior status and leadership in the field. First, by permitting him to devote a substantial proportion of his effort to his research plan. Second, by helping him to develop as a researcher thorough collaborations with colleagues who can help him expand and hone his mathematical and statistical skills. Third, by freeing up time to pursue classroom studies to help him improve his knowledgebase and refine his skills as an STD modeler and cost-effectiveness researcher. The applicant expects the skills and knowledge gained during the funding period to help him expand his research focus from HIV to STDs more broadly. By the end of the funding period, the applicant hopes to have developed the tools needed to incorporate both HIV and non-HIV STDs into dynamic models of the cost-effectiveness of prevention interventions and thereby to advance the state of the science of HIV/STD prevention cost-effectiveness.